The present invention relates to screw compressors and, more particularly, to valves for screw compressors.
Screw compressors often include oil injection systems for injecting oil into compression chambers and bearings of the compressors. The oil injection systems provide lubrication, cooling, and improved sealing within the compression chambers. Oil injection systems often use refrigeration system pressures, including compressed fluid pressures and oil pressures, to inject the oil into the compression chambers and the bearings of the compressors. For example, oil may be injected as a result of the pressure difference between the system discharge pressure and the pressure at the injection port. Oil is typically not injected during operating states where the system pressure is equal to or less than the pressure at the injection port.
To improve compressor efficiency, it is sometimes desirable to inject oil into the compression chamber at an injection port that is close to the discharge port of the compressor. However, one disadvantage of locating the injection port near the discharge port of the compressor is that relatively high pressures in the compression chamber may prevent oil from being injected when the oil pressure is relatively low. As such, many current oil injection systems locate the injection port closer to the suction port of the compressor, sacrificing efficiency in order to reduce the possibility of no oil being injected into the compression chamber.